ASME B29.15M-1997 (2017) — Steel Roller Type Conveyor Chains, Attachments, and Sprocket Teeth

⚙️ ASME B29.15M-1997 (reaffirmed 2017), Steel Roller Type Conveyor Chains, Attachments, and Sprocket Teeth, is the American National Standard defining dimensions and interchangeability requirements for steel roller type conveyor chains. Chains of this type were introduced late in the nineteenth century and met with considerable success on material conveyors and elevators. Their construction alternates roller links — links with steel bushings and rollers, where the roller contacts the sprocket teeth — with pin links made of sidebars and pins that articulate in the steel bushings of the roller links. In the 1920s, a working group of producers was formed to standardize them; in 1972 a subcommittee of American National Standards Committee B29 was appointed, with American Chain Association members from the engineering steel chain industry, to expand and update existing standards. The 1997 revision incorporates a new definition of Minimum Ultimate Tensile Strength (M.U.T.S.) and updated sprocket symbols; it was approved by ANSI on April 17, 1997, and reaffirmed in 2017.

1. Scope and Construction 📌

The Standard covers steel roller type conveyor chains, attachments, and sprocket teeth, including link dimensions, M.U.T.S., measuring load, strand length tolerance, attachment dimensions, and sprocket tooth form. The chain consists of a series of roller links (containing steel bushings with rollers that contact the sprocket teeth) alternating with pin links (sidebars and pins that articulate in the steel bushings). Pins and bushings are fixed in the sidebar pitch holes by press fits and/or mechanical locks such as flats, preventing rotation in service.

The core objective is interchangeability and interconnectability of links, attachments, and sprockets from different manufacturers. The Standard publishes controlling dimensions (Tables 2 and 3) — maximum/minimum limiting dimensions that guarantee interchangeability, not actual manufacturing sizes. Dimensions are in the decimal-inch system with metric equivalents for reference. The Standard also provides a complete sprocket tooth-form design method so chains mesh correctly with sprockets and about 5% chain pitch elongation is accommodated.

2. Chain Numbers and Principal Parameters 📏

Steel roller type conveyor chains use the B29-series numbering rule: the first two digits denote the number of 1/8 in. in pitch and the last two digits the number of 1/16 in. in pin diameter. Typical parameters of common chain numbers (reference values; see Table 1 of the Standard for exact data) are summarized below:

Note: the table is a reference summary; complete dimensions for each chain (pitch P, pin diameter D, roller diameter H, sidebar thickness T, inside width W, etc.) and the M.U.T.S., measuring load, and maximum/minimum strand lengths are given in Table 1 of the Standard.

3. Performance Parameters and Key Definitions 🔧

3.1 Minimum Ultimate Tensile Strength (M.U.T.S.)

M.U.T.S. is the minimum force at which an unused, undamaged chain could fail when subjected to a single tensile loading test, performed by slowly applying a uniaxial force to the chain sample. The Standard warns emphatically: M.U.T.S. is not a working load — it greatly exceeds the maximum force that may be safely applied, and the tensile test is destructive. Even if a chain does not visibly fail at the Minimum Ultimate Tensile Force, it has been damaged and is unfit for service.

3.2 Measuring Load and Strand Length Tolerance

The measuring load (pounds or newtons in Table 1) is the load under which a dry or lightly lubricated chain should be measured for length. New chains under measuring load may exceed the theoretical length by up to 0.38 in. per 120 in. (9.7 mm per 3048 mm) but must not fall below it; maximum and minimum strand lengths are listed in Table 1. Length tolerance ensures uniform loading of parallel strands and correct sprocket meshing.

4. Attachments and Sprocket Tooth Form 🔩

The Standard standardizes common attachments, including A-type A-1, A-2, A-42 (for mounting scrapers/flights) and K-type K-1, K-2 (for mounting cross-bars/buckets) — see Tables 4 through 8 — covering mounting interfaces for the various load-carrying elements of a conveyor. The sprocket tooth-form section provides a complete calculation system (Fig. 3 and Tables 9–10):

• Pitch diameter: D_p = P × D_pf, where the pitch diameter factor D_pf = csc(180°/N_t);
• Root diameter (max.): D_r = (P × D_pf) − H_max;
• Chain clearance circle: C_c = P(C_cf − 0.05) − U_max; outside diameter D_o = (P × C_cf) + U_max, with C_cf = cot(180°/N_t);
• Pitch line clearance: C_p = P × 0.10 to P × 0.15;
• Working face length: W_f = 0.01 × P × N_t, providing for approximately 5% chain pitch elongation;
• Other parameters: pocket radius R_p, topping radius R_t = 0.5 × P, tooth width W_t = 0.95 × minimum outside chain width, and side slope S_s ≈ 0.12 × W_t (not exceeding 0.38 in. / 9.6 mm).

5. Engineering Practice Essentials 🛠️

• 🔍 Selection workflow: determine conveying rate, lift height, and chain speed → select chain number (pitch and roller specification) → verify M.U.T.S. against a proper safety factor → choose attachment type (A or K) → design sprockets from the tooth-count formulas.
• 🔧 Sprocket design: compute pitch diameter, root diameter, and outside diameter from pitch P and tooth count N_t, then verify chain clearance and sidebar clearance so hubs and attachments do not interfere.
• 📊 Wear management: measure strand length periodically under the measuring load; consider replacement when pitch elongation exceeds roughly 2%–3%, and replace sprockets at the same time if tooth faces become hooked.
• 📋 Interchangeability management: only links and attachments made to the controlling dimensions of B29.15M are guaranteed interchangeable; mixing non-standard parts breaks meshing and load sharing.

6. Frequently Asked Questions ❓